1. Technical Field
The present invention relates to techniques for delivering multimedia content across a network, and more specifically, to techniques for transparently and adaptively transporting multimedia content across a wide range of networks.
2. Background Art
At the dawn of the 21st century, the Internet has achieved widespread use among businesses and consumers in the exchange of all forms of multimedia information. Graphic art, text, audio, video and other forms of information are continuously shared among users. In order to reduce bandwidth requirements to manageable levels, multimedia information is often stored and transported in the form of compressed bitstreams that are in a standard format. For example, in the case of audiovisual information, JPEG, Motion JPEG, MPEG-1, MPEG-2, MPEG-4, H.261 and H.263 are in widespread use.
Unfortunately, while a multitude of differing types of standardized multimedia content have been developed and made available on the Internet, there presently exists no standard way to control the access, delivery, management and protection for such content. Recognizing this need, the Motion Picture Experts Group (“MPEG”) has recently commenced the MPEG-21 Multimedia Framework initiative in order to develop a solution. As further described in International Organisation for standardisation (“ISO”) document ISO/IEC JTC1/SC29/WG11/N5231 (2002), one of the goals of MPEG-21 is develop a technique for delivering different types of content in an integrated and harmonized way, so that the content delivery process is entirely transparent to a wide spectrum of multimedia users.
In order to accomplish such a technique, part 7 of MPEG-7 proposes the concept of what is called “Digital Item Adaptation.” That concept involves the adaptation of resources and descriptions that constitute a digital item to achieve interoperable transparent access to universal multimedia from any type of terminal and network. By implementing Digital Item Adaptation, users in a network would be unaware of network and terminal-specific issues that often affect the delivery of multimedia content, such as network congestion, quality limitations, and reliability of service. It is envisioned that a diverse community of users will therefor be able to share a multimedia experience, each to his or her individual acceptable level of quality.
Probably transcoding, which avoids the need to store content in different compressed formats for different network bandwidths and different terminals, is one of the most common methods of resource adaptation. In MPEG-7, so called Transcoding Hints have been proposed in order to enable better transcoding by reducing computation complexity while preserving quality as much as possible.
Unfortunately, the proposed MPEG-7 Transcoding Hints do not provide information about feasible transcoding operators and their expected performance in order to meet specific target rates. They likewise do not provide a solution that may be useful to fulfill the multiple requirements necessary to ensure a transparent, adaptive multimedia content delivery. Accordingly, there remains a need for a technique for delivering multiple types of multimedia content over a network to a wide spectrum of multimedia users having different acceptable levels of quality.